Method and apparatus for coherent device initialization and access

ABSTRACT

A method and apparatus for enabling usage of an accelerator device in a processor socket is herein described. A set of inter-processor messages is utilized to initialize a configuration/memory space of the accelerator device. As an example, a first set of inter-processor interrupts (IPIs) is sent to indicate a base address of a memory space and a second set of IPIs is sent to indicate a size of the memory space. Furthermore, similar methods and apparatus&#39; are herein described for dynamic reconfiguration of an accelerator device in a processor socket.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of patent application Ser. No.11/958,080 filed on Dec. 17, 2007. This application is incorporatedherein by reference in its entirety.

FIELD

This invention relates to the field of computer systems and, inparticular, to accelerator devices in computer systems.

BACKGROUND

Advances in semi-conductor processing and logic design have permitted anincrease in the amount of logic that may be present on integratedcircuit devices. As a result, computer system configurations haveevolved from a single or multiple integrated circuits in a system tomultiple cores and multiple logical processors present on individualintegrated circuits. In addition, computer systems have evolved toencompass numerous different functions, such as traditional computingsystems, media storage systems, entertainment centers, audio playback,video playback, servers, etc.

As a result, the number of input/output devices to be included incomputer systems have also grown exponentially. Often, to supportfunctions that may provide too much of a load for processors in thecomputer system or are targeted at providing functions that a processorarchitecture is not fundamentally designed for, an accelerator devicemay be included in the computer system. The most common example of anaccelerator is a graphics accelerator, which provides processing powerto perform graphic and display computations. However, an accelerator mayinclude any logic to aid a processor in execution. Other examples mayinclude, a math accelerator, a matrix inversion accelerator, a videocompression accelerator, a memory access accelerator, and a networkaccelerator.

Yet, when a single accelerator is included in a system, that specificaccelerator is limited to its default intended use. Furthermore, theseaccelerators are often located “below” a chipset, i.e. off of an memorycontroller hub or interconnect controller hub through an Input/Output(I/O) bus, such as Peripheral Component Interconnect(PCI) or PCIExpress. As a result, these accelerators are commonly initializedthrough predefined I/O bus protocols and initialization procedures.However, memory access latencies are much longer for a device sittingoff an I/O bus as compared to a processor in socket.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and not intendedto be limited by the figures of the accompanying drawings.

FIG. 1 illustrates an embodiment of a system including capable ofinitializing an accelerator in a processor socket.

FIG. 2 a illustrates an embodiment of a inter-processor message.

FIG. 2 b illustrates an embodiment of a set of inter-processor messagesto initialize a memory space for a device in a processor socket.

FIG. 3 illustrates an embodiment of a flow diagram for a method ofinitialization an accelerator in a processor socket.

FIG. 4 illustrates an embodiment of a flow diagram for a method ofinitializing a memory space for an accelerator device in a processorsocket.

FIG. 5 illustrates an embodiment of a flow diagram for dynamicallyreconfiguring an accelerator device.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forthsuch as examples of specific accelerators, specific acceleratorimplementation logic, specific inter-processor messages, specific memorymapping/addressing techniques etc. in order to provide a thoroughunderstanding of the present invention. It will be apparent, however, toone skilled in the art that these specific details need not be employedto practice the present invention. In other instances, well knowncomponents or methods, such as accelerator architecture/design, addresstranslation, device initialization code/commands, and specificoperational details of computer systems, have not been described indetail in order to avoid unnecessarily obscuring the present invention.

The method and apparatus described herein are for enabling usage of anaccelerator in a processor socket. Specifically, enabling usage of anaccelerator is primarily discussed in reference to a multi-processorcomputer system capable of sending and receiving inter-processorinterrupts. However, the methods and apparatus described herein are notso limited, as they may be implemented on or in association with anyintegrated circuit device or system, such as cell phones, personaldigital assistants, embedded controllers, mobile platforms, desktopplatforms, and server platforms, as well as in conjunction with any typeof inter-processor communication.

Referring to FIG. 1, an embodiment of a system capable of enabling usageof an accelerator device in a processor socket is illustrated. Asdepicted, the computer system includes four processor sockets: 105, 110,115, and 120. Yet, any number of processor sockets may be included in acomputer system. Sockets 105, 110, 115, and 120 are coupled to hub 125.In one embodiment, hub 125 resembles a chipset. Often a chipsetcomprises two integrated circuit devices, such as a memory controllerhub (MCH) and an interconnect controller hub (ICH). In one embodimentHub 125 is the MCH coupling processors 106, 111, and 116, as well asaccelerator 121, to memory 130.

As illustrated, sockets 105, 110, 115, and 120 are coupled to hub 125through interconnect 126. In one embodiment, interconnect 126 is afront-side bus (FSB). An example of a common FSB includes a multi-dropparallel bus. Another example includes a serial point-to-pointdifferential bus, such as a Quickpath Architecture. However,interconnect 126 may include any bus or interconnect, such as a GunningTransceiver Logic (GTL) bus, a GTL+bus, a double data rate (DDR) bus, adifferential bus, a cache coherent bus, a point-to-point bus, amulti-drop bus, a serial bus, a parallel bus, or other knowninterconnect implementing any known bus protocol.

Processors 106, 111, and 116 are coupled in sockets 105, 110, and 115,respectively. Note that coupling of devices in sockets may include anycoupling, such as electrical coupling. In one embodiment, a package andcorresponding socket technology is utilized. Examples of common sockettechnologies utilized today include a Land-Grid Array (LGA)package/socket, a Pin Grid Array (PGA) package/socket, and a Ball GridArray (BGA) package/socket. However, any known apparatus forelectrically coupling processors 106, 111, and 116 into sockets 105,110, and 115 may be utilized. Furthermore, a socket may refer to anyapparatus for electrically coupling a device, such as accelerator 121,to a circuit board. Processors 106, 111, and 116 are often referred toas physical processors, but may include any style of processing element,such as a microprocessor, an embedded processor, a multi-core processor,a mutli-threaded processor, or a signal processor.

Accelerator device 121 is also electrically coupled in processor socket120. As above, accelerator device 121 potentially includes packaging tobe coupled in a corresponding processor socket. Often, sockets have aspecific land, bump, pin, or other contact patterns including specificsignal, power, and ground contacts, which couple accordingly to aprinted circuit board (PCB). As a result, in one embodiment, the packageor contacts of accelerator device 121 are placed to match theconfiguration of contacts for socket 120. Therefore, instead of anaccelerator resembling an I/O add-in card, the accelerator, in oneembodiment, may physically resemble a processor, in that the acceleratormay include a similar processor pin/bump out, as well as a packagematching a corresponding socket configuration. However, a conversionpackage may be utilized to couple an existing accelerator device in aprocessor socket.

In one embodiment, an accelerator includes a device or logic toaccelerate a processing function. As an example, a processor executingcode is able to perform some function, such as matrix inversion, duringa number of execution cycles. A matrix inversion accelerator may be ableto perform matrix inversion in a smaller number of cycles, as it isspecifically tailored to perform such computations.

In the alternative, the accelerator may not be able to perform thefunction, such as matrix inversion, at a faster rate or even an equalrate than a processor, but the accelerator potentially providesparallelization capacity for the processing function. For example,assume a floating point computation accelerator performs floating pointcalculations slower than a processor with a floating point unit. Yet,the floating point computation accelerator is deemed an accelerator, asthe accelerator is specifically tailored to provide another floatingpoint execution unit for parallel floating point execution. Therefore,in one embodiment, accelerators do not have as diverse executioncapability as a processor, and in fact, the accelerator in someembodiments may only be capable of performing a single accelerationtask/function at a time. However, in other embodiment, an acceleratormay be physically or logically portioned similarly to a multi-core ormulti-threaded processor, with each portion capable of acceleratingdifferent tasks/functions.

Examples of processing functions/tasks that an accelerator device mayaccelerate include a matrix inversion task, a graphics computation task,a floating point computation task, a memory access task, a networkaccess task, a compression task, a decompression task, an encryptiontask, a decryption task, an authentication task, a mathematicalcomputation task, and a media task. The most typical example of anaccelerator includes an I/O accelerator, such as a graphics accelerator,which is often coupled to an MCH off a peripheral connection bus.

In one embodiment, accelerator device 121 is implemented on anintegrated circuit. Examples of a logic device to implement acceleratordevice 121 includes a Programmable Array Logic (PAL) device, aProgrammable Logic Device (PLD), a Complex Programmable Logic Device(CPLD), a Field Programmable Gate Array (FPGA) device, an ApplicationSpecific Integrated Circuit (ASIC) device. In one embodiment,accelerator device 121 is a static accelerator, which is designed andimplemented to accelerate a fixed number of tasks/functions. In anotherembodiment, accelerator 121 is capable of being dynamically reconfiguredto accelerate different functions at different times. Reconfiguration ofaccelerator 121 is discussed below in reference to characters 132-133and FIG. 5.

Memory 130, as illustrated includes a system memory, to holdinitialization code 131, reconfiguration modules 132-133, andaccelerator memory space 135. An example of system memory includesdynamic random access memory (DRAM). However, any memory may be utilizedfor system memory, such as double data rate (DDR) memory, synchronousDRAM (SDRAM), buffered memory, and other known memory devices.Additionally, memory 130 is not limited to a system memory, and mayinclude other known memory devices, such as a flash memory device.

In fact, the code, modules, and memory space illustrated in memory 130may be held in a single memory device as illustrated or independentlyheld in separate memory devices. For example, a first portion ofinitialization code 131, such as Basic Input/Output Software (BIOS) orExtensible Firmware Interface (EFI) code, to initialize the computersystem and communicate with hardware at runtime may be held in a flashmemory device, while a second portion of initialization code 131, suchas a device driver for accelerator 121, may be initially held inlong-term storage, such as a hard drive, and loaded into system memoryat runtime or held in another device, such as an article of manufacture.

As stated above, initialization code 131 may include many forms of codefor system or device initialization. In one embodiment, initializationcode 131 includes BIOS or EFI code to be executed on a processor, suchas processor 106, upon boot of the computer system to initialize thesystem. As an example, when executing boot code, it is determined thatsocket 120 includes accelerator device 121. Here, boot code may alsoinclude code to initialize accelerator device 121 as described below.

In another embodiment, initialization code 131 includes code to beexecuted on a processor, such as processor 106, to initialize a memoryspace for accelerator 121. Often, a single processor is designated toexecute system management code or initialization code; however, anyprocessor including all processors 106, 111, and 116 in parallel mayexecute initialization code 131. Here, initialization code 131 mayresemble or include a device driver. Often with an accelerator devicesitting below hub 125, a device driver, when executed, mapsconfiguration registers of the device to a shared memory space utilizingspecified peripheral bus constructs/protocols, such as specifiedPCI-Express protocols.

As illustrated here, the computer system is to communicate withaccelerator device 121 through configuration space 135 in system memory.Therefore, in one embodiment, for the system and accelerator device 121to comprehend the location of memory space 135, the devicedriver/initialization code being executed on a processor, such asprocessor 106, initializes memory space 135 for accelerator 121. Inother words, the memory space is allocated and communicated toaccelerator 121, so accelerator 121 is able to comprehend its associatedmemory space. To illustrate, an oversimplified example is hereindiscussed. Upon reset, boot code held in a flash device, notillustrated, is executed, which determines that accelerator 121 is insocket 120. After initialization, an operating system loads devicedriver 131 for accelerator 121. Processor 106 executes device driver 131causing processor 106 to transmit a set of inter-processor messages tosocket 120, which was determined to be the socket including accelerator121 during boot.

In one embodiment, these inter-processor messages provide base address136 of accelerator memory space 135 and size 137 of accelerator memoryspace 135. As a result, memory space 135, which is defined by size 137added to base 136, is associated with memory space 135. Here, writes toaccelerator device 121, such as writes to registers of acceleratordevice 121, may be enabled through writes to memory space 135.Furthermore, memory space 135 may include mapped portions, such asspecific addresses, designated for configuration information commonlyheld in registers of accelerator 121. Essentially, accelerator 121 isable to map its register space in memory 130, while being able to accessmain memory with much lower latency then if accelerator 121 were placedbelow hub 125 off an I/O interconnect.

Note that a similar manner of initialization and use of accelerator 121may be utilized in a more secure execution environment, such as aVirtualization Architecture. Here, a hypervisor, such as a virtualmachine monitor (VMM), is to provide an interface between software, suchas virtual machines (VMs), and hardware, such as processors and memory.Often a hypervisor abstracts hardware to allow multiple guestapplications to run independently on the hardware. Virtual machines maybe an operating system, an application, guest software, or othersoftware to be executed on the hardware. Continuing the example above, adevice driver executing in a virtual machine may setup a similar memoryspace within a permissible memory range. Furthermore, the VMM mayintercepts memory accesses to the memory range and handle/forward themaccordingly.

However, regardless of the execution environment, in one embodiment,accelerator 121 is capable of being dynamically reconfigured. Often theusage model of a computer system changes from application to applicationand over time through different user experience. As a result, differentfunctions or tasks are to be accelerated. Instead of physicallyswitching out accelerator 121 every time a new processing task is to beaccelerated, device 121 itself, may be reconfigured. As stated above, inone embodiment, accelerator device 121 is implemented utilizingreconfigurable logic, such as a Programmable Logic Device (PLD).

As illustrated, reconfiguration modules 132 and 133 when executed are toreconfigure accelerator 121. In one embodiment, reconfiguration modules132 and 133 are code included in a device driver for accelerator 121.Essentially, a device driver provides a resemblance of a library ofmodules to reconfigure accelerator 121 to accelerate differentfunctions. As an example, reconfiguration module 132, when executed,reconfigures accelerator device 121 to accelerate matrix inversions,while reconfiguration module 133, when executed, reconfiguresaccelerator device 121 to accelerate video compression.

In one embodiment, reconfiguration of accelerator 121 occurs dynamicallyduring runtime of a computer system. As an illustrative example,processor 106 is executing a media application, which includes videocompression. However, accelerator device 121 is configured to acceleratematrix inversion. As a result, processor 106 executes reconfigurationmodule 133 to reconfigure accelerator 121 to accelerate videocompression. In one embodiment, processor 106, when executingreconfiguration module 133, transmits inter-processor messages, similarto the initialization messages described above, to reconfigureaccelerator 121. In another example, processor 106, when executingreconfiguration module 133, writes to accelerator memory space 135 toreconfigure accelerator 121. Note that a combination of direct messagingand writing to memory space may be utilized, such as a direct message toindicate reconfiguration is going to occur and writes to memory toactually provide the commands for reconfiguration.

Turning to FIG. 2 a an embodiment of a format for an inter-processormessage is illustrated. In one embodiment, an inter-processor messageincludes an inter-processor interrupt (IPI). However, inter-processormessage 200 includes any message to be routed between processor sockets105, 110, 115, and 120, without writing to shared system memory. Forexample, a write to memory space 135, updates memory, which in turn ismonitored by accelerator 121. As a result, a write to system memoryassociated with a device is often not referred to as an inter-processormessage. In contrast, an inter-processor, such as a an IPI, may bedirectly routed to socket 120 based on an identifier referenced in amessage or transaction.

As illustrated in FIG. 2 a, inter-processor message 200 includesdestination field 205 and vector 210. In one embodiment, destination 205includes a reference to a socket including an accelerator device. Forexample, an IPI destination field often includes a value, wherein firstportion 206 of the value identifies a socket and second portion 207identifies a logical processor, such as a core or thread, to receive theIPI. To illustrate, inter-processor message 200, and specifically,socket field 206 of message 200, represents socket 120, for aninter-processor message transmitted to accelerator 121. Here, a defaultvalue or any other value may be included in logical processor field 207.Or in an implementation where an accelerator device includes multipleportions to accelerate different functions, logical processor field 207may indicate an appropriate corresponding portion of the accelerator.

Furthermore, vector field 210 is to hold data or commands potentiallysupported by accelerator device 121. In one embodiment, vector 210includes sequence number field 211 and data field 212. Here, sequencenumber field 211 is to identify the order of message 200 in a set ofinter-processor messages. For example, in a bus system, such as aQuickpath architecture, which includes a serial point-to-point coherentarchitecture where bus transactions may be re-ordered, a sequence numberin sequence field 211 allows accelerator device 121 to correctly orderand aggregate inter-processor messages received out of order. However,in another embodiment, where sequence number field 211 is not utilized,data field 212 is potentially allocated a larger portion of vector 210.As stated above, data field 212 may include any information, such asdata, commands, and instructions.

Referring next to FIG. 2 b, an oversimplified embodiment of a set ofIPIs to initialization a memory space for an accelerator device isillustrated. As illustrated, first IPI 250 is an initialization IPItransmitted to begin initialization of the accelerator device. Here,destination field 205 includes the decimal value of three, i.e. binaryvalue of 011, to indicate the IPI is to be transmitted to socket three.For example, during boot of the system illustrated in FIG. 1, socket 105is associated with socket number 0, socket 110 is associated with socketnumber 1, socket 115 is associated with socket number 2, and socket 120is associated with socket number 3. Here, IPI 250 is routed to socket 3including accelerator device 121 based on at least a portion ofdestination field 205 including a value identifying socket 3.Furthermore, as the first IPI in the set, sequence number field 211 ofIPI 250 includes a value of zero.

In addition, data field 212 includes a value, which accelerator device121, recognizes as an initialization value, i.e. a predefined “magicvalue.” Based on the implementation, any predefined value may beutilized to indicate an initialization state. After the initializationIPI is received and comprehended by accelerator device 121, acceleratordevice 121 waits for IPI's to initialize its memory space. In oneembodiment, a first number of IPIs, such as IPIs 251-259, to indicate abase address of a memory space to be associated with accelerator device121. In the example illustrated, portions of the base address aretransmitted in each IPI. Also, IPIs 251-259 are ordered 1-9,accordingly, in sequence field 211. Here, the base address has 36 bits,which are sent from Lowest Significant Bit (LSB) to Most Significant Bit(MSB). However, a different embodiment includes transmitting from MSB toLSB.

After, the first number of IPIs are transmitted, a second number ofIPIs, such as IPI 260-263, are transmitted to indicate a size of thememory space. In one embodiment, the base address plus the size valuedefines the bounds of the memory space to be associated with anaccelerator device. Similar to above, IPIs 260-263 identify socket 3 indestination field 205, indicate a sequence in the set in field 211, andinclude at least a portion of the size value in each IPI. Note, thatportions of the size value may be transmitted from MSB to LSB or LSB toMSB. In addition, new ordering numbers may be restarted for each phaseof initialization, such as restarting at zero for IPI 251 and zero forIPI 260. Moreover, in one embodiment, initialization IPI 250 is nottransmitted before IPIs 251-259 or IPIs 260-263. Here, acceleratordevice 121, upon boot, enters an initialization state. As a result,initialization IPI 250 is not needed.

Initialization of a memory space for an accelerator device, as describedabove and below, in one embodiment, is in response to execution of codeon a physical processor. For example, a device driver for acceleratordevice 121 is loaded into system memory 130 and executed on processor106. As another example, the device driver or other initialization codeis included on an article of manufacture, as described below, to beexecuted on processor 106. However, any code executed on processor 106potentially results in initializing an accelerator device.

To illustrate, processor 106 when executing instructions, operations,function calls, etc. in code, such as a device driver or initializationcode, is to transmit initialization IPIS, such as the set of IPIsillustrated in FIG. 2 b to initialize memory space 135. Furthermore, theflows of FIGS. 3-5 may also be performed in response to execution ofcode by a physical processor or an accelerator device. Additionally, acompiler or other code, when executed, to compile or alterinitialization code, may insert the instructions, operations, functioncalls, and other known executable values, that when executed, are toperform the flows illustrated in FIGS. 3-5.

Although the flows of FIGS. 3-5 are illustrated in a substantiallyserial manner, any of the illustrated flows may take place in parallelwith others. The specific order of flows illustrated in FIGS. 3-5 arepurely illustrative. As a result, any flow may be performed in anyorder. For example, determining a processor socket associated with anaccelerator device in flow 300 may take place during execution ofinitialization code in flow 305.

Turning to FIG. 3, an embodiment of a flow diagram for a method ofinitializing an accelerator device is illustrated. In flow 300, aprocessor socket associated with an accelerator device is determined. Inone embodiment, boot code, when executed, is to initialize a computersystem including the accelerator. During initialization sockets andtheir contents are identified. For example, a socket including anaccelerator is polled during initialization. When executing the code, anumber or other identifier is associated with the socket including theaccelerator device. Other initialization tasks may also be performed,such as Power On Self Test (POST) and initialization of other tasks.Often code for booting a system, such as Basic Input Output Software(BIOS) code and/or Extensible Firmware Interface (EFI) code, is held ina memory device, such as a flash memory device.

In flow 305 initialization code for the accelerator is executed on aphysical processor in another socket. In one embodiment, theinitialization code for the accelerator device is included in the bootcode held in the flash device. In another embodiment, the initializationcode for the accelerator device is separate initialization code held inmemory or on an article of manufacture capable of interfacing with thecomputer system. Here, during execution of the boot code a call to theinitialization code for the accelerator may be executed. In anotherembodiment, the boot code completes execution and hands off control toan operation system or hypervisor. The hypervisor then loads andschedules execution of the initialization code, which here resemblesdevice driver code.

The physical processor, in response to executing the initializationcode, transmits a plurality of inter-processor messages from thephysical processor to the socket associated wtihthe accelerator deviceto initialize a memory space for the accelerator device in flow 310. Inone embodiment, the inter-processor messages include inter-processorinterrupts (IPIs). As an illustrative example, the inter-processormessages transmit a defined memory space. For example, a contiguoussection of physical memory is allocated to the accelerator device. Theinter-processor messages communicate the defined contiguous section ofphysical memory to the accelerator device. In one embodiment, the memoryspace is defined by a base address and a size value, which istransmitted utilizing the inter-processor messages.

A specific illustrative embodiment of a set of IPIs is illustrated inFIG. 2 b. Here, a first initialization IPI is sent to place theaccelerator device of socket 3 into an initialization mode. A firstnumber of IPIs is transmitted to the accelerator device to indicate thebase address. Note in an embodiment where sequence numbers are utilized,the accelerator device may receive the IPIs in a different order thanintended. However, the accelerator is capable of re-ordering the IPIsinto the intended order.

Furthermore, the accelerator is capable of aggregating data portions ofthe IPIs to form the entire base address from a plurality of baseaddress IPIs. As an example, each set of bits from one base address IPIis masked into a corresponding correct position within a register untilall of the transmitted data bits are held in the register. As anotherexample, the bits are serially shifted into a register. Other knownmethods and of aggregating data portions or bits may be utilized. In asimilar manner, a second number of IPIs to indicate a size value of thememory space is transmitted, received, re-ordered, and aggregated asdescribed above in reference to the base address.

Turning to FIG. 4, a specific illustrative embodiment of a flow diagramfor a method of initializing a configuration space is depicted. In flow400, a processor socket associated with an accelerator device isdetermined. Any method described above in reference to FIG. 3 or anyother known method for determining an identifier associated with adevice in a processor socket may be utilized. Note that the acceleratordevice may be any acceleration device, as described above, foraccelerating processing functions/tasks.

In flow 405, a configuration space in memory for the accelerator deviceis allocated. In one embodiment, an OS, a hypervisor, or othercontrolling code/application provides memory management. As a result, amemory space is provided by request of the OS, hypervisor, orcontrolling code. For example, with a hypervisor a space within avirtual machine (VM) memory space may be allocated. In one embodiment,the memory space or configuration space is allocated as physicallycontiguous. Therefore, the bounds of the entire memory space aredefinable by a base address and a size value. However, a non-contiguousspace may be allocated where multiple base addresses and sizes definethe configuration space.

Here, in flow 410, a first inter-processor interrupt (IPI) istransmitted to indicate a beginning of initialization. As an example, aninstruction or operation may be compiled in initialization code orinserted by a compiler in initialization code. A physical processor in acomputer system including the accelerator device, when executing theinstruction or operation, is to generate/transmit the first IPI to theaccelerator device. The processor socket determined in flow 400 isreferenced in the first IPI to enable correct routing of the first IPIto the socket including the accelerator device. An example of a firstinitialization IPI is illustrated in FIG. 2 b with reference character250. There, destination field 205 indicates the IPI is to be routed tosocket 3, has a sequence number of zero, i.e. the first IPI, andincludes a start initialization value. Note the start initializationvalue may include any “magic value,” which is recognizable by theaccelerator as a command to enter an initialization state, i.e. wait forbase address and size value IPIs.

Next, a first number of IPIs, is transmitted to the socket associatedwith the accelerator device to indicate a base address for theconfiguration space in flow 415 of FIG. 4. Referring back to FIG. 2 bagain, nine IPIs, i.e. IPIs 251-259, are sent to indicate the full baseaddress, which there includes 36 bits. However, a base address mayinclude any number of bits to reference an address and any number ofIPIs may be sent to indicate a base address. Furthermore, bits may betransmitted in any increment, such as eight bits at a time, as well asin any order, such as MSB to LSB. The accelerator device is capable ofaggregating the data portions of the first number of IPIs to form thecorrect full base address. Similarly, a second number of IPIs are sentto indicate a size value. Here, IPIs 260-261 indicate a 16 bit sizevalue, when added to the 36 bit base address defines the bounds of theconfiguration space for the accelerator device. However, once again, thesize value may include any number of bits and may be transmitted indifferent increments of bits per IPI and a different number if IPIs.

Referring next to FIG. 5, an embodiment of a flow diagram for a methodof reconfiguring an accelerator device in a processor socket isillustrated. In flow 500, reconfiguration code is executed on a physicalprocessor in a socket of a computer system. In one embodiment, thereconfiguration code is included in a device driver associated with theaccelerator device. For example, as illustrated in FIG. 1, differentreconfiguration modules may be included in the device driver, whichresembles a library of reconfiguration modules. When an accelerator isto be reconfigured to perform a different processing function, thecorresponding reconfiguration module is determined and executed toreconfigure the accelerator device. However, reconfiguration code andmodules is not limited to inclusion in a device driver, and may beincluded in any storage device able to communicate with the computersystem, such as an article of manufacture or other memory.

Next, in flow 505 reconfiguration commands are transmitted to anaccelerator device in another socket of the computer system toreconfigure the accelerator to perform a different accelerationfunction. In one embodiment, a physical processor executing thereconfiguration code transmits similar inter-processor messages asdescribed above. However, instead of an initialization command or “magicnumber” in a data field of the inter-processor message, areconfiguration command or data value is transmitted to indicate theaccelerator is to be reconfigured. Additionally, more inter-processorcommands may be transmitted to reconfigure the device.

Alternatively, after a configuration space of the accelerator device isinitialized, as described above, the physical processor, in response toexecuting the reconfiguration code, performs writes to the configurationspace to reconfigure the accelerator device. However, note thatinter-processor messaging and writes to a configuration space may beperformed in cooperation. As a first example, an inter-processor messageis sent to place the accelerator device in a reconfiguration state, i.e.wait for writes to the configuration space for re-configuration. Asanother example, for extensive reconfiguration writes to theconfiguration space are performed, while minor reconfigurations areperformed through inter-processor messaging.

As stated above, reconfiguration of an accelerator, in one embodiment,includes reconfiguring logic of an accelerator device from acceleratingone processing function to accelerate a second processing function.Examples of processing functions/tasks that an accelerator device mayaccelerate include a matrix inversion task, a graphics computation task,a floating point computation task, a memory access task, a networkaccess task, a compression task, a decompression task, an encryptiontask, a decryption task, an authentication task, a mathematicalcomputation task, and a media task. The most typical example of anaccelerator includes an I/O accelerator, such as a graphics accelerator,which is often coupled to an MCH off a peripheral connection bus.

An accelerator device may be implemented on an integrated circuit orother logic. Examples of a logic device to implement an acceleratordevice include a Programmable Array Logic (PAL) device, a ProgrammableLogic Device (PLD), a Complex Programmable Logic Device (CPLD), a FieldProgrammable Gate Array (FPGA) device, an Application SpecificIntegrated Circuit (ASIC) device.

To illustrate with an oversimplified example, assume a physicalprocessor is executing a graphics intensive program. As a result, anaccelerator in another processor socket is configured to accelerategraphics calculations, such as 3D lighting calculations or verticestranslation. In response to a context switch or during parallelexecution, the physical processor begins executing a video program withintensive video compression. As a result, during runtime of the computersystem, the processor may dynamically execute a reconfiguration module,as described above, to reconfigure the accelerator device fromaccelerating graphics calculations to accelerating video compression.

Therefore, as can be seen from above, an accelerator device may beplaced in a processor socket, which potentially enables better memorythroughput. However, without I/O bus defined protocols to initialize theaccelerator device, direct inter-processor messaging is utilized toinitialize a configuration space of the accelerator device, which may beassociated with configuration registers of the accelerator, as well as ageneral memory/communication area for the accelerator. As the size of abase address and size for the configuration space may be too large fordata vectors of existing inter-processor communication, a set ofinter-processor messages may be utilized to communicate bases and sizesof memory space. Furthermore, the accelerator may be dynamicallyreconfigured during runtime utilizing inter-processor messaging orwrites to memory to provide flexible acceleration support.

A value, as used herein, includes any known representation of a number,a state, a logical state, or a binary logical state. Often, the use oflogic levels, logic values, or logical values is also referred to as 1′sand 0′s, which simply represents binary logic states. For example, a 1refers to a high logic level and 0 refers to a low logic level. In oneembodiment, a storage cell, such as a transistor or flash cell, may becapable of holding a single logical value or multiple logical values.However, other representations of values in computer systems have beenused. For example the decimal number ten may also be represented as abinary value of 1010 and a hexadecimal letter A. Therefore, a valueincludes any representation of information capable of being held in acomputer system.

Moreover, states may be represented by values or portions of values. Asan example, a first value, such as a logical one, may represent adefault or initial state, while a second value, such as a logical zero,may represent a non-default state. In addition, the terms reset and set,in one embodiment, refer to a default and an updated value or state,respectively. For example, a default value potentially includes a highlogical value, i.e. reset, while an updated value potentially includes alow logical value, i.e. set. Note that any combination of values may beutilized to represent any number of states.

The embodiments of methods, hardware, software, firmware or code setforth above may be implemented via instructions or code stored on amachine-accessible or machine readable medium which are executable by aprocessing element. A machine-accessible/readable medium includes anymechanism that provides (i.e., stores and/or transmits) information in aform readable by a machine, such as a computer or electronic system. Forexample, a machine-accessible medium includes random-access memory(RAM), such as static RAM (SRAM) or dynamic RAM (DRAM); ROM; magnetic oroptical storage medium; flash memory devices; electrical storage device,optical storage devices, acoustical storage devices or other form ofpropagated signal (e.g., carrier waves, infrared signals, digitalsignals) storage device; etc.. For example, a machine may access astorage device through receiving a propagated signal, such as a carrierwave, from a medium capable of holding the information to be transmittedon the propagated signal.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

In the foregoing specification, a detailed description has been givenwith reference to specific exemplary embodiments. It will, however, beevident that various modifications and changes may be made theretowithout departing from the broader spirit and scope of the invention asset forth in the appended claims. The specification and drawings are,accordingly, to be regarded in an illustrative sense rather than arestrictive sense. Furthermore, the foregoing use of embodiment andother exemplarily language does not necessarily refer to the sameembodiment or the same example, but may refer to different and distinctembodiments, as well as potentially the same embodiment.

1. An apparatus comprising: an accelerator device to be electricallycoupled in a processor socket of a multi-processor socket computersystem, wherein the accelerator device is to interface with a systemmemory in the computer system through a host bus, and wherein theaccelerator device is capable of being dynamically re-configured duringruntime of the computer system from accelerating a first processing taskto accelerating a second processing task.
 2. The apparatus of claim 1,wherein the accelerator device is implemented in a device selected froma group consisting of a Programmable Array Logic (PAL) device, aProgrammable Logic Device (PLD), a Complex Programmable Logic Device(CPLD), a Field Programmable Gate Array (FPGA) device, an ApplicationSpecific Integrated Circuit (ASIC) device.
 3. The apparatus of claim 1,wherein the first processing task and the second processing task areeach independently selected from a group consisting of a matrixinversion task, a graphics computation task, a floating pointcomputation task, a memory access task, a network access task, acompression task, a decompression task, an encryption task, a decryptiontask, an authentication task, a mathematical computation task, and amedia task.
 4. The apparatus of claim 1, wherein the host bus isselected from a group consisting of a point-to-point serial bus, amulti-drop parallel bus, and a point-to-point parallel bus.
 5. Theapparatus of claim 1, wherein the accelerator device is to receive a setof inter-processor interrupts (IPIs) from at least a processor in thecomputer system to initialize an acceleration configuration space withinmemory.
 6. The apparatus of claim 5, wherein set of inter-processorinterrupts (IPIs) comprises: an initialization IPI to begininitialization of the accelerator device; a first plurality of baseaddress IPIs to indicate a physical base address for the accelerationconfiguration space; a second plurality of size IPIs to indicate a sizeof the acceleration configuration space.